package d1203;

import java.util.Scanner;

public class Demo051 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入一个字符串");
        String s = sc.nextLine();
        String[] str = s.split("a");
        String sum = "";
        for (String i : str) {
            sum = sum + i;
        }
        int len = sum.length();
        System.out.println(s.length()-len);
    }
}
